Mix these all together, just watch the consistency, if your needing thicker frosting for piping then add powdered sugar. If you need thinner, add water, just a couple drops goes a long ways. Use the thick frosting to outline the cookie. Use a piping bag + frosting tip. Use the thinner frosting to flood the rest of the cookie.

Tip: I let the frosting completely dry overnight and I went back and added white dots onto the trees, next I used a clean paint brush to push the frosting up, this gives the trees a “snowy” look.